Patent EA-000586-B1 (EA)
Title: Method for making improved sheet products of alluminum alloy
Inventor: NEWTON WILLIAM
IPC: C22C21/06
Filed: 1996-03-07
Abstract: 1. A method for fabricating an aluminum sheet product, comprising the steps of: (a) forming an aluminum alloy melt comprising; (i) from about 0.7 to about 1.3 weight percent manganese, (ii) from about 1.0 to about 1.5 weight percent magnesium, (iii) from about 0.3 to about 0.6 weight percent copper, (iv) up to about 0.5 weight percent silicon, and (v) from about 0.3 to about 0.7 weight percent iron, the balance being aluminum and incidental additional materials and impurities; (b) continuously casting said alloy melt to form a cast strip; (c) hot rolling said cast strip to reduce the thickness of said cast strip and form a hot rolled strip; (d) cold rolling said hot rolled strip to form a cold rolled strip wherein the thickness of said hot rolled strip is reduced by from about 35 percent to about 60 percent per pass; (e) annealing said cold rolled strip to form an intermediate cold mill annealed strip; and (f) further cold rolling said intermediate cold mill annealed strip to reduce the thickness of the strip and form aluminum alloy strip stock. 2. A method as recited in Claim l, wherein said aluminum alloy melt comprises from about 0.35 to about 0.5 weight percent copper. 3. A method as recited in Claim 1, wherein said hot rolling step reduces the gauge of said cast strip by at least about 70 percent. 4. A method as recited in Claim 1, wherein said method comprises the step of either: (i) annealing said hot rolled strip for at least about 0.5 hour at a temperature of from about 700 degree F (371 degree C) to about 900 degree F (482 degree C) to form a hot mill annealed strip; or (ii) cooling said hot rolled strip immediately after said hot rolling step. 5. A method as recited in Claim 1, further comprising the step of annealing said hot rolled strip immediately after said hot rolling step for at least about 0.5 hour at a temperature of from about 700 degree F (371 degree C) to about 900 degree F (482 degree C). 6. A method as recited in Claim 5, wherein said step of annealing said hot rolled strip comprises heating said hot rolled strip at a temperature of from about 800 degree F (399 degree (C) to about 850 degree F. (454 degree C). 7. A method as recited in Claim 1, wherein said step of annealing said hot rolled strip comprises annealing said hot rolled strip for from about 1 to about 5 hours. 8. A method as recited in Claim 1, wherein said step of annealing said cold rolled strip comprises annealing said cold rolled strip at a temperature of from about 600 degree F to about 900 degree F in a batch anneal oven. 9. A method as recited in Claim 6, wherein said step of annealing said cold rolled strip comprises annealing said cold rolled strip for about 3 hours. 10. A method as recited in Claim 1, wherein said step of further cold rolling said cold mill annealed strip comprises cold rolling said cold mill annealed strip to reduce the thickness of said cold mill annealed strip by from about 45 percent to about 80 percent. 11. A method as recited in Claim 1, wherein said aluminum alloy melt comprises at least about 75 weight percent scrap. 12. A method as recited in Claim 1, wherein said aluminum alloy melt comprises at least about 95 weight percent scrap. 13. A method as recited in Claim 1, further comprising the step of forming said aluminum strip stock into drawn and ironed containers. 14. A method as recited in Claim 5, wherein the cooling of said strip from said hot mill annealing step is for at least about 0.5 hour. 15. A method as recited in Claim l, wherein the annealing of said cold rolled strip is at a temperature of from about 800 degree F degree (427 degree C) to about 1050 degree F (566 degree C) in a continuous anneal step. 16. A method for fabricating an aluminum alloy strip stock, comprising the steps of: (a) forming an aluminum alloy melt derived from at least about 75 weight percent scrap, comprising; (i) from about 0.7 to about 1.3 weight percent manganese; (ii) from about 1.0 to about 1.5 weight percent magnesium; (iii) from about 0.35 to about 0.5 weight percent copper; (iv) up to about 0.5 weight percent silicon; and (v) from about 0.4 to about 0.65 weight percent iron, the balance being aluminum andincidental additional materials and impurities; (b) continuously casting said alloy melt to form a cast strip; (c) hot rolling said cast strip to reduce the thickness of said cast strip by at least about 70 percent to form a hot rolled strip; (d) annealing said hot rolled strip for at least about 0.5 hour at a temperature of from about 700 degree F (399 degree C) to about 900 degree F (484 degree C) to form a hot mill annealed strip; (e) cooling said hot mill annealed strip for at least about 0.5 hour; (f) cold rolling said hot mill annealed strip to form a cold rolled strip wherein the thickness of said hot mill annealed strip is reduced by from about 35% to about 60% per pass; (g) annealing said cold rolled strip to form a cold mill annealed strip by either: (i) batch annealing at a temperature of from about 650 degree F (343 degree C) to about 750-F(399 degree C) or; (ii) continuous annealing a-fc a temperature of from about 800 degree F (427 degree C) to about 1050 degree F (566 degree C); and (h) further cold rolling said cold mill annealed strip to reduce the thickness of the strip and fonn aluminum alloy strip stock; wherein said aluminum alloy strip stock has an after-bake yield strength of at least about 37 ksi (255MPa) and an earing of less than about 2 percent. 17. Aluminum alloy strip stock produced by continuous casting, comprising: (a) from about 0.7 to about 1.3 weight percent manganese; (b) from about 1.0 to about 1.5 weight percent magnesium; (c) from about 0.38 to about 0.45 weight percent copper; (d) from about 0.50 to about 0.60 weight percent iron; (e) up to about 0.5 weight percent silicon, the balance being aluminum and incidental additional materials and impurities. wherein said aluminum alloy strip stock has an after-bake ultimate tensile strength of at least 37 ksi (255 MPa) and an earing of less than about 2 percent. 18. The aluminum alloy strip stock as claimed in Claim 17, comprising from about 0.75 to about 1.2 weight percent manganese. 19. The aluminum alloy strip stock of Claim 17, comprising from about 0.80 to about 1.1 weight percent manganese. 20. The aluminum alloy strip stock of Claim 17, comprising from about 1.15 to about 1.45 weight percent magnesium. 21. The aluminum alloy strip stock of Claim 17, comprising from about 1.2 to about 1.4 weight percent magnesium. 22. The aluminum alloy strip stock of Claim 17, comprising from about 0.13 to about 0.25 weight percent silicon. 23. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an after-bake yield strength of at least 38 ksi (262 MPa). 24. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an after-bake yield strength of at least 40 ksi (276 MPa). 25. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an after-bake ultimate tensile strength of at least 40 ksi (276 MPa). 26. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an after-bake ultimate tensile strength of at least 41,5 ksi (286 MPa). 27. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an after-bake ultimate tensile strength of at least 43 ksi (296 MPa). 28. The aluminum alloy strip stock of Claim 17, wherein said strip stock has earing of less than 1.8 percent. 29. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an elongation of greater than 2.0 percent. 30. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an elongation of greater than 3.0 percent. 31. The aluminum alloy strip stock of Claim 17, wherein said strip stock has an elongation of greater than 4.0 percent. 32. An aluminum alloy sheet, produced by a method comprising the steps of: (a) forming an aluminum alloy melt comprising: (i) from about 0.7 to about 1.3 weight percent manganese, (ii) from about 1.0 to about 1.5 weight percent magnesium, (iii) from about 0.3 to about 0.6 weight percent copper, (iv) up to about 0.5 weight percent silicon, and (v) from about 0.3 to about 0.7 weight percent iron, the balance being aluminum and incidental additional materials and impurities; (b) continuously casting said alloy melt to form a cast strip; (c) hot rolling said cast strip to reduce the thickness of said cast strip and form a hot rolled strip; (d) annealing said hot rolled strip for at least about 0.5 hour at a temperature of from about 700 degree F (371 degree C) to about 900 degree F (482 degree C) to form a hot mill annealed strip; (e) cold rolling said hot mill annealed strip to form a cold rolled strip wherein the thickness of said hot mill annealed strip is reduced by from about 35 percent to about 60 percent per pass; (f) annealing said cold rolled strip by either: (i) batch annealing at a temperature of from about 600 degree F (315 degree C) to about 900 degree F (482 degree C) to form a cold mill annealed strip; or (ii) continuous annealing at a temperature from about 800 degree F (427 degree C0 to about 1050 degree F (566 degree C) to form a cold mill annealed strip; and (g) further cold rolling said cold mill annealed strip to reduce the thickness of the strip and form aluminum alloy strip stock; wherein said aluminum alloy sheet has an after-bake yield strength of at least about 37 ksi (255 MPa) and an earing of less than about 2 percent.